The cephalosporin antibiotic 7-(D-2-hydroxy-2-phenylacetamido)-3-(1-methyl-1H-tetrazole-5-ylthiomethyl) -3-cephem-4-carboxylic acid represented by the structural formula ##STR1## is described by Ryan in U.S. Pat. No. 3,641,021. This antibiotic, referred to herein as cefamandole, is a potent broad spectrum parenteral antibiotic with excellent activity against infectious microorganisms of the gram-negative type. Although cefamandole can be readily prepared, it has been difficult to obtain a pharmaceutically acceptable salt of cefamandole in a crystalline form of sufficient stability and purity suitable for parenteral administration.
Extensive development work on the antibiotic has afforded the O-formyl ester of cefamandole sodium salt in the gamma crystalline form as described in copending application Ser. No. 567,324, filed Apr. 11, 1975. This crystalline form of the O-formyl derivative of cefamandole sodium is suitable for parenteral administration; however, it is best administered when formulated with a mild base such as sodium carbonate. Such formulations are described in copending U.S. application Ser. No. 444,622, filed Feb. 21, 1974, now Pat. No. 3,928,592, issued Dec. 23, 1975.
A stable, crystalline form of sodium cefamandole suitable for bulk preparation and administration would avoid the necessity of preparing the O-formyl derivative form and would thus simplify the production of the antibiotic.
This invention provides a crystalline anhydrate of sodium cefamandole which is readily prepared and which possesses the stability characteristics desirable in formulations of the antibiotic.
This invention also provides a crystalline methanolate and a crystalline monohydrate of sodium cefamandole. These forms are useful as intermediate crystalline structures in the preparation of the anhydrate of sodium cefamandole.